This invention relates in general to the field of computer systems, and more particularly to a system and method for indicating the availability of a RAID controller channel.
In recent years, data intensive applications have grown more common and have made storing vast amounts of data in an online format more important. For many of these applications, the medium storing the data needs to offer high degrees of security and reliability while remaining readily accessible to a number of different requesters.
While hard drives have proven to be the paragon of secure and readily accessible storage mediums, the storage demands created by many modern applications have become too great for a single hard drive to satisfy. To meet increased demands, many computing systems employ RAID technology. RAID (xe2x80x9cRedundant Array of Independent (or Inexpensive) Disksxe2x80x9d) technology unites the capacity of several devices into a segment of common storage and, as such, introduces increased data reliability with improved data throughput capabilities. In operation, a typical RAID array has data distributed in stripes across multiple devices. This striping enables a RAID system to access data from the multiple devices at the same time.
RAID technology appears across the entire computing spectrum from personal computers to mainframes. Despite having a multiple device configuration, a RAID array may be viewed as a very large virtual device. Providing the backbone for the RAID array is a RAID controller. The RAID controller not only relays the input/output (I/O) commands to specific devices in the array, but it often provides the physical link to each of the independent devices.
Some conventional RAID controllers provide this physical link with channels that have a small computer system interface (SCSI) connector. SCSI connectors provide a standard interface that allows many different kinds of SCSI devices to be connected to the RAID controller. Occasionally, a RAID controller has an individual channel with more than one SCSI connector. For example, a RAID controller may have an internal SCSI connector and an external SCSI connector for the same channel.
By providing both an internal and an external SCSI connector, conventional RAID systems offer some degree of set up flexibility. For example, in a server, an internal connector may be used to connect an onboard hard drive to an onboard RAID controller or an add-in RAID controller. Alternatively, an external connector may be used to connect an external device to an onboard controller or an add-in RAID controller. Unfortunately, this added flexibility creates a number of operational difficulties, due to some limitations of typical SCSI busses. Generally, only 16 devices are allowed in a wide SCSI bus, and these devices have a unique SCSI ID. Moreover, termination is usually allowed only at the end of the physical bus. To enforce these limitations, typical RAID controllers are located at the end of the SCSI bus. In other words, if the internal connector of a RAID channel is already connected to an onboard device, the external connector for that channel is usually considered unavailable and should not, in typical RAID systems, be connected to an additional device.
As such, before a user connects a device to an external connector of a RAID system, the user will often identify a connector to be used and determine if that connector""s channel is availablexe2x80x94the channel is not already connected to a device via an internal connector. Conventional processes for determining channel availability are often cumbersome and time consuming. For example, in a rack mounted server application, a user may need to power down the server, remove the server from the rack, remove a portion of the server""s housing, and visually determine if an internal SCSI connector is being used.
In accordance with teachings of the present invention, a system and method for indicating channel availability are disclosed that provide significant advantages over prior developed technologies. The disclosed embodiments allow a user to accurately and expeditiously determine whether a given RAID controller channel is available.
According to one aspect of the present disclosure, a computing system may include a controller operable to manage an array of data storage devices. The devices may include, for example, disk drives with both read and write functionality. Preferably, the controller will have at least one channel, which may have both an internal and an external connector. In a preferred embodiment, the controller will be a RAID controller with multiple channels. The computing system may also include an indicator operable to indicate when a data storage device is attached to an internal connector of a given channel. The indicator may indicate attachment in any number of ways. For example, the indicator may indicate attachment with a light, a sound or some mechanical movement.
In one embodiment, the computing system may also include a test circuit. This test circuit may be conductively coupled to; the internal connector of a channel; the indicator for that channel; and a power source. The internal connector may be a SCSI connector such as a wide SCSI connector with sixty-eight pins. Preferably, the test circuit will be coupled to a specific pin of the connector. For example, the test circuit may be connected to the twentieth pin of a wide SCSI connector. In one embodiment, the specific pin may be one designated as a pin to ground by a connector protocol. A pin to ground is one that is grounded when a device is coupled to the connector and is open when no device is coupled to the connector.
In operation, the power source may cause a current to flow to the indicator only when the specific pin is grounded. As such, when a device is connected to the internal connector of a controller channel, current will flow to the indicator. If, for example, the indicator includes a light emitting diode (LED), the LED may only emit light when current flows to it or when the internal connector is connected to a device.
The disclosed embodiments will preferably allow for simplified identification of available controller channels and, as such, provide significant improvements over conventional systems. For example, the disclosed system and method may reduce or eliminate much of the labor intensive and time consuming aspects of conventional techniques for identifying available channels.
Additionally, the disclosed system and method may yield a more reliable determination of channel availability. Conventional techniques not only often require a user to visually inspect an internal connector to determine if a given channel is available, but they also require the user to know which internal connector to visually inspect. In many RAID systems, for example, there may be multiple channels. Each of these channels may have connector pairs including one external connector and one internal connector. A user seeking to connect a device to a channel at that channel""s external connector may attempt to determine if the channel is available by visually inspecting the internal connector associated with the channel. Unfortunately, the user may not know which internal connector to inspect and, as a result, may visually inspect the wrong internal connector.
Other technical advantages will be apparent to those of ordinary skill in the art in view of the following specification, claims, and drawings.